The use of SU-8 material in the production of neural sensors has grown recently. Despite its widespread application, a detailed systematic quantitative analysis concerning its biocompatibility in the central nervous system is lacking. In this immunohistochemical study, we quantified the neuronal preservation and the severity of astrogliosis around SU-8 devices implanted in the neocortex of rats, after a 2 months survival.

We found that the density of neurons significantly decreased up to a distance of 20 μm from the implant, with an averaged density decrease to 24 ± 28% of the control. At 20 to 40 μm distance from the implant, the majority of the neurons was preserved (74 ± 39% of the control) and starting from 40 μm distance from the implant, the neuron density was control-like. The density of synaptic contacts – examined at the electron microscopic level – decreased in the close vicinity of the implant, but it recovered to the control level as close as 24 μm from the implant track. The intensity of the astroglial staining significantly increased compared to the control region, up to 560 μm and 480 μm distance from the track in the superficial and deep layers of the neocortex, respectively. Electron microscopic examination revealed that the thickness of the glial scar was around 5–10 μm thin, and the ratio of glial processes in the neuropil was not more than 16% up to a distance of 12 μm from the implant.

Our data suggest that neuronal survival is affected only in a very small area around the implant. The glial scar surrounding the implant is thin, and the presence of glial elements is low in the neuropil, although the signs of astrogliosis could be observed up to about 500 μm from the track. Subsequently, the biocompatibility of the SU-8 material is high. Due to its low cost fabrication and more flexible nature, SU-8 based devices may offer a promising approach to experimental and clinical applications in the future.

SU-8材料在神经传感器生产中的用途最近有所增加。尽管其广泛应用，但缺乏关于其在中枢神经系统中的生物相容性的详细的系统定量分析。在这项免疫组织化学研究中，我们对存活2个月后植入大鼠新皮层的SU-8装置周围的神经元保存和星形胶质沉着的严重程度进行了量化。

我们发现，距植入物20μm处的神经元密度显着降低，平均密度降低至对照组的24±28％。在距植入物20至40μm的距离处，大多数神经元得以保留（对照组的74±39％），并且从距植入物40μm的距离开始，神经元密度呈对照样。在电子显微镜下检查，突触接触的密度在植入物附近逐渐降低，但在距植入物轨迹近24μm的地方恢复到控制水平。与对照区域相比，星形胶质细胞染色的强度显着增加，分别距新皮层的表层和深层距磁道的距离分别为560μm和480μm。

我们的数据表明，神经元存活仅在植入物周围很小的区域受到影响。植入物周围的神经胶质疤痕很薄，神经胶质中神经胶质元素的含量很低，尽管可以在距轨迹约500μm的地方观察到星形胶质化的迹象。随后，SU-8材料的生物相容性很高。由于其低成本的制造和更灵活的性质，基于SU-8的设备在将来可能为实验和临床应用提供有前途的方法。